There are numerous types and arrangements of centrifugal clutch constructions in which one or more clutch shoes are retained in retracted position by springs until sufficient centrifugal force acts on the shoes to overcome the force of retaining springs, whereupon the clutch shoes pivot and swing outwardly and engage a stationary clutch housing or drum.
Many of these clutch constructions have a pair of arcuate shaped clutch shoes which are pivotally mounted on a clutch backing plate or rotor and which are arranged in an end-to-end relationship with respect to each other. The backing plate usually is fixed to a drive shaft or hub for rotation with the drive shaft. These clutch shoes have various spring arrangements which bias the shoes toward and retain the shoes in retracted position. It is this spring retaining tension which is overcome by the centrifugal force enabling the clutch shoes to engage the driven member.
These clutch shoes have a variety of configurations and constructions. Each shoe generally has an arcuate-shaped member formed of stamped steel and consists of a flat shoe web with an outer curved shoe table on which a strip of friction material is mounted for frictionally engaging a driven drum. In order to reduce the cost of these clutch shoes, fewer component parts and steps of assembly is desired without sacrificing reliability and efficiency.
Many types of existing clutch shoes are formed by a pair of similar, stamped steel flat members which are welded or riveted together to form the shoe web. An arcuate strip then is welded to the outer edge of the formed web to provide the shoe table on which the friction strip is attached. These clutch shoes are pivotally mounted on the clutch backing plate by a pin or bushing which is telescopically mounted in a sleeve which is welded or brazed in an opening formed in the shoe web.
This construction and method of assembly requires at least four separate parts, namely, a pair of matching shoe webs, an outer shoe table, and a bushing mounting sleeve. Likewise, several welding, brazing and/or riveting operations are required for assembling these four components. Each of these separate components and the manufacturing and assembling thereof increases the cost of the final clutch shoe construction.
There is no known existing clutch shoe construction and method of making of which we are aware, that enables the clutch shoe to be formed by a pair of stamped steel members which are joined without welding or brazing operations, and which eliminates the use of a bushing mounting sleeve.